Vertical take-off and landing aircraft using hybrid electric propulsion system

ABSTRACT

A vertical take-off and landing aircraft using a hybrid electric propulsion system includes an engine, a generator that produces electric power using power supplied by the engine, and a battery that stores the produced electric power. A motor receives the electric power stored in the battery and electric power produced by the generator but not stored in the battery and provides the power to a thrust generating apparatus. A controller selects either silence mode or normal mode, and determines the amount of electric power stored in the battery and the amount of electric power not stored in the battery from the electric power supplied to the motor. In the silence mode, the controller supplies only the electric power stored in the battery and controls a duration by adjusting output power of motor. In the normal mode, the controller supplies electric power not stored in the battery.

BACKGROUND Field of the Invention

The following embodiments relate to a vertical take-off and landing(VTOL) aircraft using a hybrid-electric propulsion system.

Description of Related Art

A vertical take-off and landing aircraft based on a rotary wing, such asa helicopter, does not need separate takeoff and landing facilities andequipment, but has lower high-speed flight performance, high-altitudeperformance, and flight endurance performance than an equivalentfixed-wing aircraft. Compared to a fixed-wing aircraft for which variouspropulsion systems—from an electric motor to a jet engine—are possible,a vertical take-off and landing (VTOL) aircraft which depends only onthe shaft horsepower of an engine has a limited selection of appropriatepropulsion systems as the weight of the aircraft decreases. Inparticular, a reciprocating engine that is widely used in a smallaircraft with a maximum take-off weight (MTOW) of about 10 Kg to about300 Kg has a very small output-to-weight ratio of about 2. Therefore, inorder to supply power needed for vertical take-off and landing, anengine needs to be very bulky, and the propulsion system is excessivelyheavier compared to an empty weight of the aircraft. Thus, it isdifficult to obtain a payload and endurance time required for a mission.Therefore, a propulsion system using a battery and an electric motor iswidely used in a small aircraft. However, due to limitations of thecurrent technology on batteries with low energy density, it isimpossible to provide sufficient endurance time required for a mission.

A long endurance flight requires an energy source with high specificenergy and a power device capable of converting the said energy where asa vertical take-off and landing requires an energy source with highspecific power and a device capable of converting the said power.

However, an energy source or a power generating device with both highspecific energy and high specific power doesn't exist, so in general, anenergy source and a power generating device with high specific energyare installed in an aircraft. Since vertical take-off and landing of anaircraft need much energy, and a propulsion system including a powergenerating device should be designed to supply sufficient power evenduring the vertical take-off and landing, such a configurationsignificantly increases the total weight of the propulsion system beyondthe weight needed for a flight, causing an increase in weight of theaircraft and inefficiency of the propulsion system.

Recent and continuing efforts include utilizing an energy source withhigh specific energy and an energy source with high specific power atthe same time to decrease the weight of the propulsion system, increaseefficiency, and provide longer endurance time.

BRIEF SUMMARY OF THE INVENTION Technical Problem

The hybrid vertical take-off and landing aircraft according to anembodiment may determine required power on the basis of the currentposition of a thrust generating apparatus, thus providing high flightefficiency.

The hybrid vertical take-off and landing aircraft according to anembodiment may supply only electric power stored in the battery to amotor in silence mode, thus providing low-noise flight without noisegenerated by an engine and a generator (or, an alternator).

The hybrid vertical take-off and landing aircraft according to anembodiment may control a first thrust generating apparatus that receivespower from the engine and a second thrust generating apparatus thatreceives electric power produced by the generator depending on verticalflight or horizontal flight, thus providing high flight efficiency.

Technical Solution

The hybrid vertical take-off and landing aircraft according to anembodiment may include an engine, a generator configured to produceelectric power using power supplied by the engine, a battery configuredto store the electric power produced by the generator, a motorconfigured to receive at least one of the electric power stored in thebattery and electric power produced by the generator but not stored inthe battery and provide the power to at least one thrust generatingapparatus, and a controller configured to select either silence mode ornormal mode, and determine the amount of electric power stored in thebattery and the amount of electric power not stored in the battery fromthe electric power supplied to the motor, based on the selected mode,wherein, in the silence mode, the controller configured to supply onlythe electric power stored in the battery to the motor, and control aduration by adjusting output power of motor, and wherein, in the normalmode, the controller configured to supply electric power not stored inthe battery to the motor.

Technical solutions of the present invention are not limited to theaforesaid, and other technical solutions that are not described hereinwould be clearly understood by those skilled in the art from thefollowing description and the accompanying drawings.

Advantageous Effect of the Invention

The hybrid vertical take-off and landing aircraft according to anembodiment may determine required power on the basis of the currentposition of a thrust generating apparatus, thus providing high flightefficiency.

The hybrid vertical take-off and landing aircraft according to anembodiment may supply only electric power stored in the battery to amotor in the silence mode, thus providing low-noise flight without noisegenerated by an engine and a generator

The hybrid vertical take-off and landing aircraft according to anembodiment may control a first thrust generating apparatus that receivespower from the engine and a second thrust generating apparatus thatreceives electric power produced by the generator depending on verticalflight or horizontal flight, thus providing high flight efficiency.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for describing a hybrid vertical take-off andlanding aircraft according to an embodiment.

FIG. 2 is a block diagram showing a propulsion system of a hybridvertical take-off and landing aircraft according to an embodiment.

FIG. 3 is a diagram for describing a battery management system (BMS)according to an embodiment.

FIG. 4 is a block diagram showing a propulsion system of a serial-typehybrid vertical take-off and landing aircraft according to anembodiment.

FIG. 5 is a diagram for describing a change in position of a propulsiongenerating device according to an embodiment.

FIG. 6 is a diagram showing a mission profile of a hybrid verticaltake-off and landing aircraft during a mission according to anembodiment.

FIG. 7 is a diagram showing a mission profile of a hybrid verticaltake-off and landing aircraft during a mission according to anotherembodiment.

FIG. 8 is an operational flowchart for describing an electric powercontrol method of a hybrid vertical take-off and landing aircraftaccording to an embodiment.

FIG. 9 is a block diagram showing a propulsion system of a serial-typehybrid vertical take-off and landing aircraft according to anotherembodiment.

FIG. 10 is an operational flowchart for describing entry into silencemode according to an embodiment.

FIG. 11 is an operational flowchart for describing a method ofcontrolling a hybrid vertical take-off and landing aircraft according toanother embodiment.

FIG. 12 is a diagram for describing a mixed type hybrid verticaltake-off and landing aircraft according to an embodiment.

FIG. 13 is a block diagram showing a propulsion system of a mixed typehybrid vertical take-off and landing aircraft according to anembodiment.

FIG. 14 is a diagram for describing first to third periods according toan embodiment.

FIG. 15 is an operational flowchart for describing a method ofcontrolling a mixed type hybrid vertical take-off and landing aircraftaccording to an embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The hybrid vertical take-off and landing aircraft according to anembodiment may include an engine, a generator configured to produceelectric power using power supplied by the engine, a battery configuredto store the electric power produced by the generator, a motorconfigured to receive at least one of the electric power stored in thebattery and electric power produced by the generator but not stored inthe battery and provide the power to at least one thrust generatingapparatus, and a controller configured to select either silence mode ornormal mode, and determine the amount of electric power stored in thebattery and the amount of electric power not stored in the battery fromthe electric power supplied to the motor, based on the selected mode,wherein, in the silence mode, the controller configured to supply onlythe electric power stored in the battery to the motor, and control aduration by adjusting output power of motor, and wherein, in the normalmode, the controller configured to supply electric power not stored inthe battery to the motor.

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings. However, the present invention is notrestricted or limited to the embodiments. Also, like reference numeralsin the drawings denote like elements.

1. Hybrid Vertical Take-Off and Landing Aircraft

FIG. 1 is a diagram for describing a hybrid vertical take-off andlanding aircraft according to an embodiment.

Referring to FIG. 1, a hybrid vertical take-off and landing (a hybridVTOL) aircraft 100 may be represented as an aircraft having wings thatperforms take-off and landing in a vertical direction and generates liftforce. Thus, the hybrid vertical take-off and landing aircraft 100 cantake off and land without needing a runway. The hybrid vertical take-offand landing aircraft 100 may include fixed wings 111 and 112 that arefixed on the body of the aircraft and rotary wings 121, 122, and 123that rotationally move to generate thrust. For example, the rotary wings121, 122, and 123 may include a propeller, a rotor, or a ducted fan. Thehybrid vertical take-off and landing aircraft 100 may have a largerflight range and a longer flight time than a rotary-wing aircraft suchas a helicopter. Also, the hybrid vertical take-off and landing aircraft100 may not need an additional take-off and landing apparatus, such as acatapult.

Also, the hybrid vertical take-off and landing aircraft 100 may requiremore power than a fixed-wing aircraft during take-off and landing. Thus,the hybrid vertical take-off and landing aircraft 100 may use a highspecific power battery.

In an embodiment, the hybrid vertical take-off and landing aircraft 100may supply power to the rotary wings 121, 122, and 123 by a hybridmethod. Here, the hybrid method may include a serial hybrid method, aparallel hybrid method, and a mixed hybrid method.

In the hybrid vertical take-off and landing aircraft 100, the serialhybrid method is a method of driving the rotary wings 121, 122, and 123using an electric motor. In this method, an engine may supply power to agenerator (or, an alternator) the generator may produce electric powerusing the power supplied from the engine, and the motor may drive therotary wings 121, 122, and 123 using the electric power produced by thegenerator.

In the hybrid vertical take-off and landing aircraft 100, the parallelhybrid method is a method of driving the rotary wings 121, 122, and 123using an engine and a motor. In this method, a generator may produceelectric power using power supplied from an engine, and the motor maydrive the rotary wings 121, 122, and 123 using the power produced by thegenerator. In addition, the engine may drive the rotary wings 121, 122,and 123 using the power of the engine.

In the hybrid vertical take-off and landing aircraft 100, the mixedhybrid method mixes the serial hybrid method and the parallel hybridmethod. In this method, some of the rotary wings 121, 122, and 123 maybe driven in the serial hybrid method, and the others may be driven inthe parallel hybrid method.

In an embodiment, according to a flight operation of the hybrid verticaltake-off and landing aircraft 100, the rotary wings 121 and 122 may betilted. As an example, the rotary wings 121 and 122 may be tilted upwardwhen the hybrid vertical take-off and landing aircraft 100 is taking offor landing vertically and may be tilted forward when the hybrid verticaltake-off and landing aircraft 100 is flying horizontally.

A configuration, an operation, and an example of the hybrid verticaltake-off and landing aircraft 100 will be described in detail below.

2. Serial-Type Hybrid Vertical Take-Off and Landing Aircraft

FIG. 2 is a block diagram showing a propulsion system of a hybridvertical take-off and landing aircraft according to an embodiment.

Referring to FIG. 2, a propulsion system 200 of the hybrid verticaltake-off and landing aircraft may include a fuel tank 210, an engine220, a generator 230, an electric power controller 240, a controller250, a battery 260, a motor driver 270, and a motor 280. Also, thepropulsion system 200 may further include a propeller. Since thepropulsion system 200 is of the serial hybrid method, the propeller maybe driven by the motor 280 having electric power as a power source,instead of being supplied with power from the engine 220.

The fuel tank 210 may supply fuel to the engine 220. The fuel tank 210may be variously designed to have a capacity range that may satisfy atarget flight time. Also, the fuel tank 210 may be designed not to incurdamage or fuel leakage in all conditions that may occur while theaircraft is carrying out a mission.

The engine may burn the fuel supplied from the fuel tank 210 to generatemechanical power. In the serial hybrid method, the engine 220 may bedriven to provide power that is used by a generator to produce electricpower.

Output power of the engine 220 may be variously designed in a range ofoutput power that may sufficiently supply power needed for safe flightof the hybrid vertical take-off and landing aircraft. Also, the engine220 may be turned on or off by the generator 230.

The generator 230 may produce electric power using the power suppliedfrom the engine 220. In an embodiment, the generator 230 may be anintegrated starter and generator (ISG). Also, the generator 230 mayconvert the power of the engine 220 into electrical energy and mayconvert the electric energy into mechanical energy. In this case, thegenerator 230 may convert the power of the engine 220 into 3-phase ACelectric power. In this case, a line-to-line voltage of the 3-phase ACelectric power may be lower than a voltage of the battery 260. Also, thegenerator 230 may control the supply of power to the engine 220 tocontrol the startup of the engine 220. For example, the generator 230may block the supply of power to the engine 220 to turn off the engine220 when the generator 230 does not produce electric power and maysupply power to the engine 220 to turn on the engine 220 when thegenerator 230 produces electric power.

The electric power controller 240 may control electric power producedand supplied by the propulsion system 200. The electric power controller240 may be represented as a power management unit (PMU) or a powercontroller (PCU). The electric power controller 240 may monitor theamount of electric power required by the propulsion system 200 and maycontrol the generator 230 to supply the power required by the propulsionsystem 200 on the basis of a result of the monitoring.

In an embodiment, the electric power controller 240 may include aconverter configured to convert AC electric power into DC electricpower. For example, the converter may include a 3-phase inverter, whichmay convert 3-phase AC electric power produced by a generator into DCelectric power. The electric power controller 240 may supply the DCelectric power to the battery 260 or an auxiliary battery. For example,the electric power controller 240 may control the supply such that theDC electric power supplied to the battery 260 is less than the DCelectric power supplied to the auxiliary battery. Also, the electricpower controller 240 may directly supply the DC electric power to themotor 280.

Also, the electric power controller 240 may determine whether thegenerator 230 will produce electric power by considering the amount ofelectric power stored in the battery 260, the amount of electric powerto be supplied to the motor, etc.

Also, the electric power controller 240 may control a throttle of theengine 220 and the generator 230 to control the startup of the engine220. For example, the electric power controller 240 may control athrottle signal of the engine 220 through a converter (e.g., a 3-phaseinverter) to adjust revolutions per minute (RPM) of the engine 220 andmay control torque of the generator 230 through the converter.

Also, the electric power controller 240 may monitor informationregarding a fuel level indicating the remaining amount of fuel in thefuel tank 210, RPM of the engine 220, a rotor position of the generator230, a voltage and current of power generated by the generator 230, anda voltage and current provided to the motor driver 270 by the battery260.

The controller 250 may control elements associated with the flight ofthe propulsion system 200. In an embodiment, the controller 250 maycontrol the fuel tank 210, the engine 220, the generator 230, theelectric power controller 240, the battery 260, and the motor driver270. The controller 250 may monitor battery state such as the fuel levelof the fuel tank 210, the amount of electric power stored in the battery260, and temperature of the battery 260. Also, the controller 250 mayinclude a communication system, an identification system, a navigationsystem, an autopilot apparatus, an electronic aircraft managementsystem, an anti-collision system, a radar system, etc. The controller250 may be represented as avionics.

In the block diagram shown in FIG. 2, the controller 250 and theelectric power controller are shown as being separate from each other,but are not limited thereto. Accordingly, the controller 250 and theelectric power controller 240 may be configured as one unit.

The battery 260 may store the DC electric power obtained by theconversion of the electric power controller 240 and may supply thestored DC electric power in the motor 280. In an embodiment, the battery260 may be a lithium polymer (LiPo) battery and may include a pluralityof cells. Also, the battery 260 may be controlled by a batterymanagement system (BMS). The battery 260 and the BMS will be describedin detail with reference to FIG. 3.

The motor driver 270 may control the motor 280. In an embodiment, themotor driver 270 may receive a control signal from the controller 250 orthe electric power controller 240 and may control the motor 280according to the received control signal.

The motor 280 may receive electric power from at least one of theelectric power controller 240 and the battery 260 and may drive thepropeller of the hybrid vertical take-off and landing aircraft. In anembodiment, the motor 280 may be a brushless DC electric motor (BLDCmotor) or a permanent-magnet synchronous motor (PMSM).

FIG. 3 is a diagram for describing a battery management system (BMS)according to an embodiment.

Referring to FIG. 3, the BMS 310 may monitor a state of the battery 320and may control the battery 320. The BMS 310 may perform a control suchthat charging states and cell voltages are equal among a plurality ofbattery cells included in the battery 320. Also, the BMS 310 may controltemperature of the battery 320 using a cell heating module 351 and acell cooling module 352 of the temperature control module 350. In anembodiment, in order to maintain performance of the battery 320, the BMS310 may control temperature of the battery 320 by considering altitudevariation of the hybrid vertical take-off and landing aircraft.

Also, the BMS 310 may prevent overcharging of the battery 320. In anembodiment, the battery 320 may supply electric power to a motor 370through an electric current measuring unit 330, a connection unit 340,and a motor driver 360. The electric current measuring unit 330 maymeasure a level of an electric current supplied from the battery 320 tothe motor 370. When the electric current level measured by the electriccurrent measuring unit 330 is less than or equal to a predeterminedthreshold amount, the BMS 310 may control the connection unit 340 to beturned on and may control the motor 370 to receive electric power fromthe battery 320. When the electric current level measured by theelectric current measuring unit 330 exceeds the predetermined thresholdamount, the BMS 310 may control the connection unit 340 to be turned offto block the supply of electric power to the motor 370 of the battery320 in order to prevent overcharging.

Also, the BMS 310 may estimate a state of health (SoH), a state ofcharge (SoC), a state of function (SoF), etc. of each of a plurality ofbattery modules. Here, the SoH may indicate how much the performance ofthe battery 320 has deteriorated compared to when manufactured, the SoCmay indicate information regarding the amount of electric chargeaccommodated by the battery 320, and the SoF may indicate informationregarding how consistent the performance of the battery 320 is with apredetermined condition. Also, the BMS 310 may provide the SoH, the SoC,and the SoF to the electric power controller or the controller.

3. Hybrid Vertical Take-Off and Landing Aircraft with Variable Positionof Thrust Generating Apparatus

FIG. 4 is a block diagram showing a propulsion system of a serial-typehybrid vertical take-off and landing aircraft according to anembodiment.

Referring to FIG. 4, a propulsion system 400 of the hybrid verticaltake-off and landing aircraft may include an engine 410, a generator420, a controller 430, a battery 440, a motor 450, and a thrustgenerating apparatus 460. In an embodiment, the above descriptions ofthe hybrid vertical take-off and landing aircraft with reference toFIGS. 1 to 3 may be applied to the propulsion system 400 of the hybridvertical take-off and landing aircraft of FIG. 4.

The engine 410 may burn fuel to generate mechanical power and may supplythe generated power to the generator 420.

The generator 420 may produce electric power using the power suppliedfrom the engine 410. In an embodiment, the generator 420 may be anintegrated starter and generator (ISG). The ISG may produce AC electricpower using the power supplied from the engine 410.

The battery 440 may store the electric power produced by the generator420. In this case, the electric power stored in the battery 440 may beDC electric power. The battery 440 may supply electric power to themotor 450 according to the control of the controller 430.

The thrust generating apparatus 460 may generate thrust, and the hybridvertical take-off and landing aircraft may fly using the generatedthrust. In this case, the thrust generating apparatus 460 may beprovided as at least one apparatus. As an example, the rotary wings 121,122, and 123 of FIG. 1 may be included in the thrust generatingapparatus 460.

The position of the thrust generating apparatus 460 may be variable.Here, the position does not refer to the absolute position of the thrustgenerating apparatus 460, but may be defined as a direction in which anaxis of rotation (or a center (e.g., a core)) of the thrust generatingapparatus 460 is directed. Thus, the current position of the thrustgenerating apparatus 460 may vary depending on the direction of the axisof rotation of the thrust generating apparatus 460.

The motor 450 may receive at least one of electric power stored in thebattery 440 and electric power produced by the generator 420 but notstored in the battery 440 and may provide the power to the thrustgenerating apparatus 460. The motor 450 may receive required powerindicating electric power supplied to the motor 450 according to thecontrol of the controller 430. In an embodiment, the motor 450 may be abrushless DC electric motor (BLDC motor) or a permanent-magnetsynchronous motor (PMSM).

The controller 430 may control the engine 410, the generator 420, thebattery 440, the motor 450, and the thrust generating apparatus 460. Inan embodiment, the controller 430 may convert AC electric power producedby the generator 420 into DC electric power. For example, the controller430 may include a converter, which may convert AC electric powerproduced by the ISG into DC electric power.

Also, the controller 430 may control the position of the thrustgenerating apparatus 460 to be variable. The controller 430 may move theposition of the thrust generating apparatus 460, that is, the directionof the axis of rotation of the thrust generating apparatus 460 between afirst direction from the tail of the hybrid vertical take-off andlanding aircraft to the head of the hybrid vertical take-off and landingaircraft and a second direction that is an upward directionperpendicular to the first direction. Here, the first direction mayrefer to the forward direction in which the hybrid vertical take-off andlanding aircraft flies, and the second direction may refer to the upwarddirection that is perpendicular to the forward direction in which thehybrid vertical take-off and landing aircraft flies. The axis ofrotation of the thrust generating apparatus 460 being in the firstdirection may be defined as a first position of the thrust generatingapparatus 460, and the axis of rotation of the thrust generatingapparatus 460 being in the second direction may be defined as a secondposition of the thrust generating apparatus 460.

When the hybrid vertical take-off and landing aircraft takes off orlands vertically, the controller 430 may move the position of the thrustgenerating apparatus 460 to the second position. When the position ofthe thrust generating apparatus 460 moves to the second position and theaxis of rotation of the thrust generating apparatus 460 is in the seconddirection, the thrust generating apparatus 460 may generate thrust in adirection perpendicular to the hybrid vertical take-off and landingaircraft. The thrust generated in the vertical direction may facilitatethe vertical take-off and landing of the hybrid vertical take-off andlanding aircraft.

Also, when the hybrid vertical take-off and landing aircraft is in alevel flight (e.g., a cruise flight or loitering flight), the controller430 may move the position of the thrust generating apparatus 460 to thefirst position. When the position of the thrust generating apparatus 460moves to the first position and the axis of rotation of the thrustgenerating apparatus 460 is in the first direction, the thrustgenerating apparatus 460 may generate thrust in a direction horizontalto the hybrid vertical take-off and landing aircraft. The thrustgenerated in the horizontal direction may facilitate the horizontalflight of the hybrid vertical take-off and landing aircraft.

Also, the position of the thrust generating apparatus 460 is not limitedto the first position and the second position. Accordingly, thecontroller 430 may move the position of the thrust generating apparatus460 to a point between the first position and the second position. In anembodiment, the controller 430 may change a direction of the axis ofrotation of the thrust generating apparatus 460 from the seconddirection to the first direction according to altitude and flight speedwhen the hybrid vertical take-off and landing aircraft climbs and maychange the direction of the axis of rotation of the thrust generatingapparatus 460 from the first direction to the second direction accordingto altitude and flight speed when the hybrid vertical take-off andlanding aircraft descends.

The controller 430 may confirm the current position of the thrustgenerating apparatus 460 and determine required power on the basis ofthe confirmed current position of the thrust generating apparatus 460.

Since the controller 430 can control the position of the thrustgenerating apparatus 460, the controller 430 may confirm the most recentcontrol command that controlled the position of the thrust generatingapparatus 460 to confirm the current position of the thrust generatingapparatus 460. Also, the controller 430 may confirm informationregarding the current position of the thrust generating apparatus 460from the thrust generating apparatus 460.

With the same amount of electric power supplied to the motor 450, theflight distance of the hybrid vertical take-off and landing aircraft mayvary depending on the current position of the thrust generatingapparatus 460. For example, when the current position of the thrustgenerating apparatus 460 is the first position and also the hybridvertical take-off and landing aircraft supplies a predetermined amountof electric power to the motor 450 to achieve horizontal flight, thehybrid vertical take-off and landing aircraft may have a large amount ofmovement, compared to vertical flight. Likewise, when the currentposition of the thrust generating apparatus 460 is the second positionand also the hybrid vertical take-off and landing aircraft supplies apredetermined amount of electric power to the motor 450 to achievehorizontal flight, the hybrid vertical take-off and landing aircraft mayhave a small amount of movement, compared to vertical flight. This isbecause, when the current position of the thrust generating apparatus460 is the first position, thrust may be generated by the thrustgenerating apparatus 460 in a horizontal direction and the thrustgenerated in the horizontal direction may act as resistance force duringthe vertical flight. Also, thrust generated in a vertical direction whenthe current position of the thrust generating apparatus 460 is thesecond position may act as resistance force during the horizontalflight. When the current position of the thrust generating apparatus 460is the first position, in order to make the amount of movement upon thevertical flight equal to the amount of movement upon the horizontalflight, output power of the motor 450 upon the vertical flight should begreater than output power of the motor 450 upon the horizontal flight.That is, the output power of the motor 450 of the propulsion system 400may vary depending on the current position of the thrust generatingapparatus 460. Thus, the controller 430 may determine the output powerof the motor 450 on the basis of the current position of the thrustgenerating apparatus 460. Also, since the output power of the motorcorresponds to required power, the controller 430 may determine therequired power on the basis of the current position of the thrustgenerating apparatus 460.

In an embodiment, threshold output power of the motor 450 may bedetermined on the basis of the current position of the thrust generatingapparatus 460. For example, first threshold output power indicatingthreshold output power of the motor 450 upon the horizontal flight andsecond threshold output power indicating a threshold output power of themotor 450 upon the vertical flight may be predetermined. When a resultof the confirmation of the current position of the thrust generatingapparatus 460 is that the thrust generating apparatus 460 is in thefirst position, the controller 430 may control the output power of themotor to be equal to or less than the first threshold output power. Onthe other hand, when the thrust generating apparatus 460 is in thesecond position, the controller 430 may control the output power of themotor 450 to be equal to or less than the second threshold output power.

In an embodiment, the controller 430 may receive a piloting signal ofthe hybrid vertical take-off and landing aircraft through acommunication interface, control the output power of the motor 450 byconsidering the current position of the thrust generating apparatus 460according to the piloting signal, and determine required power on thebasis of the controlled output power of the motor 450. Here, thecommunication interface may refer to an interface through which thepropulsion system 400 communicates with an external apparatus. As anexample, the communication interface may be included in the controller430. Also, the piloting signal may include a piloting instruction thatcontrols acceleration, deceleration, or altitude variation of the hybridvertical take-off and landing aircraft and may include a pilotinginstruction that controls target altitude, target speed, or targetacceleration of the hybrid vertical take-off and landing aircraft. As anexample, the propulsion system 400 may receive the piloting signal froma ground station.

In an embodiment, the amount of electric power required by the motor 450may be determined on the basis of the current position of the thrustgenerating apparatus 460. For example, when the current position of thethrust generating apparatus 460 is the first position, the amount ofelectric power required by the motor 450 when the hybrid verticaltake-off and landing aircraft is flying horizontally may be less thanthe amount of electric power required by the motor 450 when the hybridvertical take-off and landing aircraft is flying vertically. This isbecause, when the current position of the thrust generating apparatus460 is the first position and also the hybrid vertical take-off andlanding aircraft is flying vertically, the thrust generated in thehorizontal direction acts as resistance force, thus increasing load onthe motor 450. Also, when the current position of the thrust generatingapparatus 460 is the second position, the amount of electric powerrequired by the motor 450 when the hybrid vertical take-off and landingaircraft is flying horizontally may be greater than the amount ofelectric power required by the motor 450 when the hybrid verticaltake-off and landing aircraft is flying vertically. Thus, the controller430 may control the output power of the motor 450 according to thepiloting signal on the basis of the amount of electric power required bythe motor 450 that varies depending on the current position of thethrust generating apparatus 460.

Also, the controller 430 may control the output power of the motor 450to reach at least one of target altitude, target speed, and targetacceleration of the hybrid vertical take-off and landing aircraftincluded in the piloting signal, by considering the current position ofthe thrust generating apparatus. For example, on condition that thetarget speed included in the piloting signal is 80 km/h, the controller430 may set the output power of the motor 450 as 1.5 kW when the currentposition of the thrust generating apparatus 460 is the first positionand may set the output power of the motor 450 as 4 kW when the currentposition of the thrust generating apparatus 460 is the second position.

Also, the controller 430 may determine the amount of electric powerstored in battery 440 and the amount of electric power not stored in thebattery 440 from the power supplied to the motor 450, on the basis ofthe determined required power. According to the determined amount ofelectric power, the controller 430 may perform a control to supply onlythe electric power stored in the battery 440 to the motor 450, supplyonly the electric power not stored in the battery 440 to the motor 450,or supply both the electric power stored in the battery 440 and theelectric power not stored in the battery 440 to the motor 450.

In an embodiment, the controller 430 may supply the power not stored inthe battery 440 to the motor 450 preferentially over the power stored inthe battery 440. This is to enhance fuel efficiency of the hybridvertical take-off and landing aircraft. For example, when the amount ofrequired power is greater than the amount of electric power not storedin the battery 440, the controller 430 may perform a control to supplyall of the power not stored in the battery 440 and supply, to the motor450, electric power corresponding to a difference between the amount ofelectric power not stored in the battery 440 and the amount of requiredpower out of the electric power stored in the battery 440. An anotherexample, when the amount of required power is equal to the amount ofelectric power not stored in the battery 440, the controller 430 maysupply only the amount of electric power not stored in the battery 440to the motor 450. As still another example, when the amount of requiredpower is less than the amount of electric power not stored in thebattery 440, the controller 430 may perform a control to supply only thepower not stored in the battery 440 to the motor 450 and store, in thebattery 440, the remaining electric power of the power not stored in thebattery 440 other than the power supplied to the motor 450.

In another embodiment, the controller 430 may supply the power stored inthe battery 440 to the motor 450 preferentially over the power notstored in the battery 440. For example, when the hybrid verticaltake-off and landing aircraft lands, the controller 430 may supply theelectric power stored in the battery 440 to the motor 450 preferentiallyover the power not stored in the battery 440. This is to consume thepower stored in the battery 440 before the hybrid take-off and landingaircraft lands in order to enhance fuel efficiency. For example, whenthe amount of required power is greater than the amount of electricpower stored in the battery 440, the controller 430 may perform acontrol to supply all of the power stored in the battery 440 and supply,to the motor 450, electric power corresponding to a difference betweenthe amount of electric power stored in the battery 440 and the amount ofrequired power out of the electric power not stored in the battery 440.As another example, when the amount of required power is equal to orless than the amount of electric power stored in the battery 440, thecontroller 430 may perform a control to supply only the electric powerstored in the battery 440 to the motor 450.

In an example of FIG. 4, the controller 430 may be represented as oneunit. However, the controller 430 may be composed of a first controllerand a second controller. Also, embodiments of the present invention arenot limited thereto. The controller 430 may be composed of a pluralityof units. As an example, the first controller may correspond to thecontroller 250 of FIG. 2, and the second controller may correspond tothe electric power controller 240 of FIG. 2.

The first controller may control an operation of the second controller,the movement of the hybrid vertical take-off and landing aircraft, andthe communication between the hybrid vertical take-off and landingaircraft and a ground station. Also, the first controller may confirmthe current position of the thrust generating apparatus 460 anddetermine required power on the basis of the confirmed current positionof the thrust generating apparatus 460.

The controller 2 may determine the amount of electric power stored inbattery 440 and the amount of electric power not stored in the battery440 from the power supplied to the motor 450, on the basis of thedetermined required power. Also, the second controller may adjust theamount of electric power produced by the generator 420 and the amount ofelectric power stored in the battery 440 on the basis of the requiredpower.

Also, the second controller may include a converter, which may convertAC electric power produced by an ISG into DC electric power and storethe DC electric power in the battery 440 or directly supply the DCelectric power to the motor 450. Also, the second controller may supplythe DC electric power to an auxiliary battery. The first controller maybe driven by receiving the DC electric power from the auxiliary battery.

Also, the second controller may control the ISG to adjust the amount ofproduction of the AC electric power. For example, when the amount ofrequired power is less than the amount of electric power that isproduced by the ISG but not stored in the battery, the second controllermay control the ISG to produce electric power by the amount of requiredpower.

FIG. 5 is a diagram for describing a change in position of a propulsiongenerating device according to an embodiment.

Referring to FIG. 5, thrust generating apparatuses 520 and 530 of thehybrid vertical take-off and landing aircraft 510 may vary in position.When the hybrid vertical take-off and landing aircraft 510 is in ahorizontal flight such as a cruising flight or a loitering flight, asshown in (a), the hybrid vertical take-off and landing aircraft 510 maytilt the axes of rotation of the thrust generating apparatuses 520 and530 in the forward direction. Also, when the hybrid vertical take-offand landing aircraft 510 is in a vertical flight such as verticaltake-off or vertical landing, as shown in (b), the hybrid verticaltake-off and landing aircraft 510 may tilt the axes of rotation of thethrust generating apparatuses 520 and 530 in the upward direction. Thisis to generate thrust in a direction in which the hybrid verticaltake-off and landing aircraft 510 intends to fly by tilting the thrustgenerating apparatuses 520 and 530. Also, the hybrid vertical take-offand landing aircraft 510 may confirm the current positions of the thrustgenerating apparatuses 520 and 530, determine required power indicatingpower supplied to the motor on the basis of the current positions of thethrust generating apparatuses 520 and 530, and determine the amount ofelectric power stored in the battery and the amount of electric powernot stored in the battery from the power supplied to the motor on thebasis of the determined required power.

FIG. 6 is a diagram showing a mission profile of a hybrid verticaltake-off and landing aircraft during a mission according to anembodiment.

Referring to FIG. 6, a horizontal axis of a graph of FIG. 6 mayrepresent range, and a vertical axis may represent altitude. It isassumed that the hybrid vertical take-off and landing aircraft in FIG. 6is the same as the hybrid vertical take-off and landing aircraft 510shown in FIG. 5. In time points 611 to 618, the hybrid vertical take-offand landing aircraft may control the thrust generating apparatus to makea flight. In this case, the hybrid vertical take-off and landingaircraft may determine required power on the basis of the currentposition of the thrust generating apparatus and may determine the amountof electric power stored in the battery and the amount of electric powerproduced by the generator but not stored in the battery on the basis ofthe determined required power.

From time point 611 to time point 612, the hybrid vertical take-off andlanding aircraft may take off vertically. In this case, the axis ofrotation of the thrust generating apparatus may be directed in theupward direction. For example, the hybrid vertical take-off and landingaircraft may determine the amount of electric power stored in thebattery as 2 kW and the amount of electric power not stored in thebattery as 2 kW from the required power.

Also, the hybrid vertical take-off and landing aircraft may make aclimbing flight from time point 612 to time point 613. In this case, theaxis of rotation of the thrust generating apparatus may be changed fromthe upward direction to the forward direction or may be fixed to theupward direction or forward direction. As an example, the hybridvertical take-off and landing aircraft may make a climbing flight for 10minutes and may determine the amount of electric power stored in thebattery as 1 kW and the amount of electric power not stored in thebattery as 2 kW from the required power. Also, the hybrid verticaltake-off and landing aircraft may make a cruising flight from time point613 to time point 614 or from time point 615 to time point 616. In thiscase, the axis of rotation of the thrust generating apparatus may bedirected in the forward direction. For example, the hybrid verticaltake-off and landing aircraft may fly at the speed of 80 km/h and maydetermine the electric power stored in the battery as 1 kW and theamount of electric power not stored in the battery as 1 kW from therequired power. Also, the hybrid vertical take-off and landing aircraftmay enter dash mode that rapidly increases the speed from time point 615to time point 616. For example, in the dash mode, the hybrid verticaltake-off and landing aircraft may fly at the speed of 120 km/h and maydetermine the electric power stored in the battery as 1 kW and theamount of electric power not stored in the battery as 2 kW from therequired power. Also, the hybrid vertical take-off and landing aircraftmay supply only the electric power not stored in the battery to themotor to make a cruising flight.

Also, the hybrid vertical take-off and landing aircraft may make aloitering flight from time point 614 to time point 615. In this case,the axis of rotation of the thrust generating apparatus may be directedin the forward direction. For example, the hybrid vertical take-off andlanding aircraft may make a loitering flight using only the electricpower not stored in the battery and may deliver electric power producedby the generator but not stored in the battery to the motor whilecharging the battery with electric power produced by the generator.Also, the hybrid vertical take-off and landing aircraft may enter thesilence mode that supplies only the electric power stored in the batteryto the motor. In this case, the hybrid vertical take-off and landingaircraft may turn off its engine to prevent the generator from producingelectric power.

Also, the hybrid vertical take-off and landing aircraft may make adescent flight from time point 616 to time point 617. In this case, theaxis of rotation of the thrust generating apparatus may be changed fromthe forward direction to the upward direction or may be fixed to theupward direction or forward direction. As an example, the hybridvertical take-off and landing aircraft may make the descent flight usingonly the electric power not stored in the battery and may deliverelectric power produced by the generator but not stored in the batteryto the motor while charging the battery with electric power produced bythe generator.

Also, the hybrid vertical take-off and landing aircraft may landvertically from time point 617 to time point 618. In this case, the axisof rotation of the thrust generating apparatus may be directed in theupward direction. For example, the hybrid vertical take-off and landingaircraft may preferentially supply the electric power stored in thebattery to the motor in order to enhance fuel consumption efficiency.

FIG. 7 is a diagram showing a mission profile of a hybrid verticaltake-off and landing aircraft during a mission according to anotherembodiment.

Referring to FIG. 7, a horizontal axis of a graph of FIG. 7 mayrepresent range, and a vertical axis may represent altitude. It isassumed that the hybrid vertical take-off and landing aircraft in FIG. 7is the same as the hybrid vertical take-off and landing aircraft 510shown in FIG. 5. In time points 711 to 728, the hybrid vertical take-offand landing aircraft may control the thrust generating apparatus to makea flight. In this case, the hybrid vertical take-off and landingaircraft may determine required power on the basis of the currentposition of the thrust generating apparatus and may determine the amountof electric power stored in the battery and the amount of electric powerproduced by the generator but not stored in the battery on the basis ofthe determined required power.

From time point 711 to time point 712, the hybrid vertical take-off andlanding aircraft may take off vertically. In this case, the axis ofrotation of the thrust generating apparatus may be directed in theupward direction. Also, the hybrid vertical take-off and landingaircraft may make a climbing flight from time point 712 to time point713. In this case, the axis of rotation of the thrust generatingapparatus may be changed from the upward direction to the forwarddirection or may be fixed to the upward direction or forward direction.Also, the hybrid vertical take-off and landing aircraft may make acruising flight from time point 713 to time point 714. In this case, theaxis of rotation of the thrust generating apparatus may be directed inthe forward direction. Also, the hybrid vertical take-off and landingaircraft may enter the dash mode that rapidly increases the speed fromtime point 713 to time point 714. Also, the hybrid vertical take-off andlanding aircraft may supply only the electric power not stored in thebattery to the motor to make a cruising flight. Also, the hybridvertical take-off and landing aircraft may make a descent flight fromtime point 714 to time point 717. In this case, the axis of rotation ofthe thrust generating apparatus may be changed from the forwarddirection to the upward direction or may be fixed to the upwarddirection or forward direction. As an example, the hybrid verticaltake-off and landing aircraft may make the descent flight using only theelectric power not stored in the battery and may deliver electric powerproduced by the generator but not stored in the battery to the motorwhile charging the battery with electric power produced by thegenerator. Also, while making the descent flight, from time point 715 totime point 716, the hybrid vertical take-off and landing aircraft maymake a loitering flight. For example, the hybrid vertical take-off andlanding aircraft may make a loitering flight using only the electricpower not stored in the battery and may deliver electric power producedby the generator but not stored in the battery to the motor whilecharging the battery with electric power produced by the generator.Also, the hybrid vertical take-off and landing aircraft may enter thesilence mode that supplies only the electric power stored in the batteryto the motor. In this case, the hybrid vertical take-off and landingaircraft may turn off its engine to prevent the generator from producingelectric power. Also, the hybrid vertical take-off and landing aircraftmay land vertically from time point 717 to time point 718. In this case,the axis of rotation of the thrust generating apparatus may be directedin the upward direction.

Also, the hybrid vertical take-off and landing aircraft may take offvertically again from time point 721 to time point 722. The hybridvertical take-off and landing aircraft may make a climbing flight fromtime point 722 to time point 723, make a cruising flight from time point723 to time point 724, make a loitering flight from time point 724 totime point 725, and make a cruising flight again from time point 725 totime point 726. As an example, when the hybrid vertical take-off andlanding aircraft makes a loitering flight or cruising flight, the hybridvertical take-off and landing aircraft may enter the silence mode thatsupplies only the electric power stored in the battery to the motor.Also, the hybrid vertical take-off and landing aircraft may make adescent flight from time point 726 to time point 727 and may landvertically from time point 727 to time point 728. FIG. 8 is anoperational flowchart for describing an electric power control method ofa hybrid vertical take-off and landing aircraft according to anembodiment.

Referring to FIG. 8, the hybrid vertical take-off and landing aircraftmay confirm the current position of at least one thrust generatingapparatus whose position is variable (810). Also, the hybrid verticaltake-off and landing aircraft may determine required power according toa required flight state on the basis of the confirmed current positionof the at least one thrust generating apparatus (820).

Also, the hybrid vertical take-off and landing aircraft may determinethe amount of first electric power and the amount of second electricpower from the electric power supplied to the motor that provides powerto the at least one thrust generating apparatus on the basis of thedetermined required power (830). Here, the first electric power mayrefer to electric power stored in the battery from electric powerproduced by the generator using the power supplied by the engine, andthe second electric power may refer to electric power not stored in thebattery from the electric power produced by the generator.

The above descriptions with reference to FIGS. 1 to 7 may be applied tothe method of controlling electric power of the hybrid vertical take-offand landing aircraft shown in FIG. 8, and thus a detailed descriptionthereof will be omitted.

4. Operation Mode of Hybrid Vertical Take-Off and Landing Aircraft

FIG. 9 is a block diagram showing a propulsion system of a serial-typehybrid vertical take-off and landing aircraft according to anotherembodiment.

Referring to FIG. 9, a propulsion system 900 of the hybrid verticaltake-off and landing aircraft may include an engine 910, a generator920, a controller 930, a battery 940, and a motor 950. In an embodiment,the descriptions of the hybrid vertical take-off and landing aircraftwith reference to FIGS. 1 to 3 may be applied to the propulsion system900 of FIG. 9.

The engine 910 may burn fuel to generate mechanical power and may supplythe generated power to the generator 920.

The generator 920 may produce electric power using the power suppliedfrom the engine 910. In an embodiment, the generator 920 may be anintegrated starter and generator (ISG). The ISG may produce AC electricpower using the power supplied from the engine 410.

The battery 940 may store the electric power produced by the generator920. In this case, the electric power stored in the battery 940 may beDC electric power. The battery 940 may supply electric power to themotor 950 according to the control of the controller 930.

The motor 950 may receive at least one of electric power stored in thebattery 940 and electric power produced by the generator 920 but notstored in the battery 440 and may provide the power to at least onethrust generating apparatus. The motor 950 may receive required powerindicating electric power supplied to the motor 950 according to thecontrol of the controller 930. In an embodiment, the motor 450 may be abrushless DC electric motor (BLDC motor) or a permanent-magnetsynchronous motor (PMSM).

The controller 930 may control the engine 910, the generator 920, thebattery 940, and the motor 950. In an embodiment, the controller 930 mayconvert AC electric power produced by the generator 920 into DC electricpower. For example, the controller 930 may include a converter (e.g.,3-phase inverter), which may convert AC electric power produced by theISG into DC electric power.

The controller 930 may select an operation mode of the propulsion system900. Here, the operation mode may include silence mode and normal mode.The silence mode may refer to an operation mode that supplies electricpower stored in the battery to the motor and does not supply electricpower produced by the generator but not stored in the battery to themotor. Since the generator need not generate electric power in thesilence mode, the controller 930 may control the generator 920 to stopproducing the electric power and may control the engine 910 to be turnedoff. Thus, noise generated by the hybrid vertical take-off and landingaircraft may be decreased.

The normal mode may refer to an operation mode that supplies theelectric power not stored in the battery 940 to the motor 950. Thus, inthe normal mode, the controller 930 may perform a control to supply onlythe electric power not stored in the battery to the motor 950 or tosupply the electric power stored in the battery 940 and also theelectric power not stored in the battery 940 to the motor 950. Also, thenormal mode may include dash mode. The dash mode may refer to anoperation mode that rapidly accelerates the hybrid vertical take-off andlanding aircraft. Thus, the required power of the motor may increase inthe dash mode.

In an embodiment, the controller 930 may receive a piloting signal usinga communication interface. Here, the piloting signal may include apiloting instruction that controls the operation mode. The controller930 may extract the piloting instruction from the piloting signal andmay select the silence mode or the normal mode according to the pilotinginstruction.

Also, the piloting signal may include information regarding coordinatesor time at which the hybrid vertical take-off and landing aircraftenters the silence mode. In this case, the controller 930 may select thesilence mode in response to the reaching of the silence mode entrycoordinates or time included in the piloting signal. For example, forthe case in which that the piloting signal includes a controlinstruction to enter the silence mode from point A to point B, thecontroller 930 may select the silence mode as the operation mode whenthe hybrid vertical take-off and landing aircraft reaches point A andmay select the normal mode as the operation mode when the hybridvertical take-off and landing aircraft reaches point B.

Also, before reaching the silence mode entry coordinates or timeincluded in the piloting signal, the controller 930 may store electricpower to be used in the silence mode in the battery 940. To this end,the controller 930 may adjust the amount of electric power produced bythe generator 920 in the normal mode to store the electric powerproduced by the generator 920 in the battery so that the silence mode isentered when the silence mode entry coordinates or time included in thepiloting signal is reached. In the above example, the controller 930 mayestimate an expected time taken to reach point A and may determinewhether the hybrid vertical take-off and landing aircraft can make aflight in the silence mode during a predetermined duration when theelectric power produced by the generator 920 is stored in the battery upto the expected time by using the current amount of electric currentproduced by the generator 920. When it is determined that the flight isimpossible, the controller 930 may increase the amount of electric powerproduced by the generator 920, store the produced electric power in thebattery 940, and thereby secure the amount of electric power sufficientto make a flight in the silence mode for the predetermined duration.Also, the piloting signal may include information regarding the durationof the silence mode. For example, the piloting signal may include acontrol instruction to maintain the silence mode for 5 minutes. In thiscase, in the normal mode, the controller 930 may determine whether thesilence mode can be maintained for the duration. When it is determinedthat the silence mode cannot be maintained for the duration, thecontroller 930 may adjust the amount of production of the generator 920before reaching the silence mode entry coordinates or time included inthe piloting signal. Thus, the controller 930 may store the producedelectric city in the battery 940 in order to maintain the silence modefor the duration.

Also, the piloting signal may include information regarding coordinatesor time at which the hybrid vertical take-off and landing aircrafttake-off and landing aircraft exits the silence mode. In this case, thecontroller 930 may select the normal mode in response to the reaching ofthe silence mode exit coordinates or time included in the pilotingsignal. For example, when the piloting signal includes a controlinstruction to exit the silence mode after 10 minutes, the controllermay select the normal mode as the operation mode 10 minutes afterreceiving the piloting signal. Also, the piloting signal may include apiloting instruction that controls acceleration, deceleration, oraltitude variation of the hybrid vertical take-off and landing aircraftand may include a piloting instruction that controls target altitude,target speed, or target acceleration of the hybrid vertical take-off andlanding aircraft. The controller 930 may control output power of themotor 950 according to the piloting signal and may determine requiredpower of the motor 950 on the basis of the output power of the motor950.

In an embodiment, when the amount of required power is greater than theamount of electric power stored in the battery in the silence mode, thecontroller 930 may control the output power of the motor 950 to decreasethe amount of required power to the amount of electric power stored inthe battery 940 or less. For example, for the case in which thatelectric power corresponding to 80 km/h is 4 kW and electric powercorresponding to 60 km/h is 3 kW, when the amount of required power is 4kW and the electric power stored in the battery is 3 kW, the controller930 may adjust the speed of the hybrid vertical take-off and landingaircraft by decreasing the amount of required power to 3 kW. In thesilence mode, only the electric power stored in the battery 940 issupplied to the motor 950. Thus, the output power of the motor 950 maycorrespond to the electric power stored in the battery 940. Accordingly,when the amount of required power is greater than the electric powerstored in the battery 940, the motor 950 cannot receive electric powerequal to the required power from the battery 940. Accordingly, thecontroller 930 may control the amount of required power to supply onlythe electric power stored in the battery 940 to the motor 950.

Also, in the silence mode, the controller 930 may supply only theelectric power stored in the battery 940 to the motor 950 when theamount of required power is equal to or less than the amount of electricpower stored in the battery 940.

In an embodiment, the controller 930 may control the output power of themotor 950 to control the duration of the silence mode. Since the silencemode uses only the electric power stored in the battery 940, theduration over which the silence mode can be maintained may be limited.Also, the duration may decrease when the required power is large, andmay increase when the required power is small because consumption of theelectric power stored in the battery decreases. Thus, the controller 930may compare the required power and the power stored in the battery 940to estimate the duration of the silence mode.

Also, the controller 930 may transmit information associated with thesilence mode to a piloting apparatus configured to pilot the hybridvertical take-off and landing aircraft through a communicationinterface. For example, the controller 930 may transmit a notificationmessage including information regarding the amount of electric powerstored in the battery 940, the duration of the silence mode, the amountof required power, the amount of change in duration according to achange in the required power, etc. to the piloting apparatus configuredto pilot the hybrid vertical take-off and landing aircraft. In anembodiment, when the estimated duration is equal to or less than apredetermined time, the controller 930 may transmit the notificationmessage through the communication interface. For example, the controller930 may generate the notification message including informationregarding the amount of electric power stored in the battery 940, theduration of the silence mode, etc. and may transmit the generatednotification message to the piloting apparatus configured to pilot thehybrid vertical take-off and landing aircraft.

Also, when the estimated duration is equal to or less than apredetermined time, the controller 930 may decrease the amount ofrequired power may decrease the current amount of required power orless. As the current amount of required power decreases, the amount ofelectric power supplied to the motor 950 of the battery 940 maydecrease, and thus the duration of the silence mode may increase.

Also, the piloting signal may include information regarding at least oneof a target speed and target acceleration of the hybrid verticaltake-off and landing aircraft. In this case, the controller 930 maycontrol the output power of the motor 950 to reach the target speed orthe target acceleration and may determine required power indicatingelectric power supplied to the motor 950 on the basis of the controlledoutput power of the motor 950. For example, when the hybrid verticaltake-off and landing aircraft is flying at a speed of 60 km/h, thepiloting signal received by the controller 930 may include a pilotinginstruction to fly at the target speed of 120 km/h. In this case, sincethe hybrid vertical take-off and landing aircraft is rapidlyaccelerated, the controller 930 may select the dash mode included in thenormal mode as the operation mode. As the hybrid vertical take-off andlanding aircraft enters the dash mode, the controller 930 may increasethe output power of the motor 950 to allow the hybrid vertical take-offand landing aircraft to reach the speed of 120 km/h and may determinerequired power corresponding to the increased output power of the motor950. Also, in order to supply electric power corresponding to therequired power to the motor 950, the controller 930 may supply theelectric power stored in battery 940 and also the electric powerproduced by the generator 920 but not stored in the battery 940 to themotor 950.

In an example of FIG. 9, the controller 930 may be represented as oneunit. However, the controller 930 may be composed of a first controllerand a second controller. Also, embodiments of the present invention arenot limited thereto. The controller 930 may be composed of a pluralityof units. As an example, the first controller may correspond to thecontroller 250 of FIG. 2, and the second controller may correspond tothe electric power controller 240 of FIG. 2.

The first controller may select the silence mode or the normal mode asthe operation mode of the propulsion system 900.

The second controller may determine the amount of electric power storedin battery 940 and the amount of electric power not stored in thebattery 940 from the power supplied to the motor 950, on the basis ofthe selected mode.

FIG. 10 is an operational flowchart for describing entry into silencemode according to an embodiment.

Referring to FIG. 10, the hybrid vertical take-off and landing aircraftmay receive a piloting signal through a communication interface (1010).

Also, the hybrid vertical take-off and landing aircraft may confirm asilence mode entry instruction included in the piloting signal (1020).

Also, the hybrid vertical take-off and landing aircraft may confirm theamount of electric power stored in the battery and the amount ofrequired power (1030).

Also, the hybrid vertical take-off and landing aircraft may determinewhether the amount of electric power stored in the battery is equal toor greater than the amount of required power (1040). When it isdetermined that the amount of electric power stored in the battery issmaller than the amount of required power, the hybrid vertical take-offand landing aircraft may set the amount of required power to be theamount of electric power stored in the battery or less (1041). Also,when it is determined that the amount of electric power stored in thebattery is equal to or greater than the amount of required power, thehybrid vertical take-off and landing aircraft may determine whether theduration of the silence mode is equal to or greater than a predeterminedduration (1050). Here, the predetermined duration may include apredetermined default duration or a duration included in the pilotingsignal. When it is determined the duration of the silence mode is lessthan the predetermined duration, the hybrid vertical take-off andlanding aircraft may charge the battery to increase the duration of thesilence mode to the predetermined duration in the normal mode or greater(1051). In this case, the hybrid vertical take-off and landing aircraftmay control the amount of electric power produced by the generatoraccording to the amount of electric power needed to charge the battery.After charging the battery, the hybrid vertical take-off and landingaircraft may determine whether the duration of the silence mode is equalto or greater than the predetermined duration again.

Also, when it is determined that the duration of the silence mode isequal to or greater than the predetermined duration, the hybrid verticaltake-off and landing aircraft may enter the silence mode (1060).

FIG. 11 is an operational flowchart for describing a method ofcontrolling a hybrid vertical take-off and landing aircraft according toanother embodiment.

Referring to FIG. 11, the hybrid vertical take-off and landing aircraftmay select, as an operation mode, the silence mode that supplies onlythe electric power stored in the battery to the motor, adjusts theoutput power of the motor, and controls the duration or the normal modethat supplies the electric power produced by the generator but notstored in the battery to the motor. Here, the battery may store electricpower produced by the generator using the power supplied by the engine,and the motor may receive at least one of the electric power stored inthe battery and the electric power produced by the generator but notstored in the battery and may provide the power to at least one thrustgenerating apparatus (1110).

Also, the hybrid vertical take-off and landing aircraft may determinethe amount of electric power stored in the battery and the amount ofelectric power not stored in the battery from the power supplied to themotor on the basis of the selected mode (1120).

The above descriptions with reference to FIGS. 1 to 10 may be applied tothe method of controlling the hybrid vertical take-off and landingaircraft shown in FIG. 11, and thus a detailed description thereof willbe omitted.

5. Mixed Type Hybrid Vertical Take-Off and Landing Aircraft

FIG. 12 is a diagram for describing a mixed type hybrid verticaltake-off and landing aircraft according to an embodiment.

Referring to FIG. 12, as shown in (a) and (b), a hybrid verticaltake-off and landing aircraft 1210 may include a first rotary wing 1220and second rotary wings 1231, 1232, and 1233. The hybrid verticaltake-off and landing aircraft 1210 may supply power to the first rotarywing 1220 and the second rotary wings 1231, 1232, and 1233 in a mixedtype hybrid method. In an embodiment, the first rotary wing 1220 may beconnected with an engine to directly receive power from the engine, andthe second rotary wings 1231, 1232, and 1233 may receive electric powerproduced by the generator. Here, the generator may receive power fromthe engine and produce electric power. The first rotary wing 1220 maydirectly receive power from the engine, and the second rotary wings1231, 1232, and 1233 may receive electric power converted from the powergenerated from the engine, thus decreasing energy conversion loss of thegenerator, increasing fuel efficiency, and increasing thrust of thehybrid vertical take-off and landing aircraft 1210.

FIG. 13 is a block diagram showing a propulsion system of a mixed typehybrid vertical take-off and landing aircraft according to anembodiment.

Referring to FIG. 13, a propulsion system 1300 of the hybrid verticaltake-off and landing aircraft may include an engine 1310, a generator1320, a controller 1330, a battery 1340, a motor 1350, a first thrustgenerating apparatus 1360, and a second thrust generating apparatus1370. In an embodiment, the above descriptions of the hybrid verticaltake-off and landing aircraft with reference to FIGS. 1 to 3 may beapplied to the propulsion system 1300 of the hybrid vertical take-offand landing aircraft of FIG. 13.

The engine 1310 may burn fuel to generate mechanical power and maysupply the generated power to the generator 1320. In an embodiment, theengine 1310 may supply power to the generator 1320 and supply power tothe first thrust generating apparatus 1360. The engine 1310 may alsosupply power to the generator 1320 and the first thrust generatingapparatus 1360 at the same time. The generator 1320 may produce electricpower using the power supplied from the engine 1310. In an embodiment,the generator 1320 may be an integrated starter and generator (ISG). TheISG may produce AC electric power using the power supplied from theengine 1310.

The battery 1340 may store the electric power produced by the generator1320. In this case, the electric power stored in the battery 1340 may beDC electric power. The battery 1340 may supply electric power to themotor 1350 according to the control of the controller 1330.

The first thrust generating apparatus 1360 may be directly connectedwith the engine 1310 and may generate thrust using the power supplied bythe engine 1310. Thus, the first thrust generating apparatus 1360 may bedriven using fuel other than electricity as a power source. In anembodiment, the position of the first thrust generating apparatus 1360may be fixed or variable. Here, the positions of the first thrustgenerating apparatus 1360 and the second thrust generating apparatus1370 do not refer to absolute positions of the first thrust generatingapparatus 1360 and the second thrust generating apparatus 1370, and thusmay be defined as directions in which axes of rotation (or centers) ofthe first thrust generating apparatus 1360 and the second thrustgenerating apparatus 1370 are directed. Also, as an example, the firstthrust generating apparatus 1360 may be installed at the head of thehybrid vertical take-off and landing aircraft. As an example, the rotarywing 1130 of FIG. 11 may be included in the first thrust generatingapparatus 1360.

The second thrust generating apparatus 1370 may be driven by the motor1350 to generate thrust. In this case, the second thrust generatingapparatus 1370 may be provided as at least one apparatus. As an example,the second rotary wings 1231, 1232, and 1233 of FIG. 12 may be includedin the second thrust generating apparatus 1370. Also, the position ofthe second thrust generating apparatus 1370 may be variable.

The motor 1350 may receive at least one of electric power stored in thebattery 1340 and electric power produced by the generator 1320 but notstored in the battery 1340 and may provide the power to the secondthrust generating apparatus 1370. The motor 1350 may receive requiredpower indicating electric power supplied to the motor 1350 according tothe control of the controller 1330. In an embodiment, the motor 450 maybe a brushless DC electric motor (BLDC motor) or a permanent-magnetsynchronous motor (PMSM).

The controller 1330 may control the position of the first thrustgenerating apparatus 1360 or the second thrust generating apparatus 1370to be variable. For example, the controller 1330 may move the positionof the first thrust generating apparatus 1360 or the second thrustgenerating apparatus 1370, that is, the direction of the axis ofrotation of the first thrust generating apparatus 1360 or the secondthrust generating apparatus 1370 between a first direction from the tailof the hybrid vertical take-off and landing aircraft to the head of thehybrid vertical take-off and landing aircraft and a second directionthat is an upward direction perpendicular to the first direction. Here,the first direction may refer to a forward direction in which the hybridvertical take-off and landing aircraft flies, and the second directionmay refer to an upward direction that is perpendicular to the forwarddirection in which the hybrid vertical take-off and landing aircraftflies. Here, the axis of rotation of the first thrust generatingapparatus 1360 or the second thrust generating apparatus 1370 beingdirected in the first direction may be defined as a first position ofthe first thrust generating apparatus 1360 or the second thrustgenerating apparatus 1370, and the axis of rotation of the first thrustgenerating apparatus 1360 or the second thrust generating apparatus 1370being directed in the second direction may be defined as a secondposition of the first thrust generating apparatus 1360 or the secondthrust generating apparatus 1370.

Also, the controller 1330 may control the engine 1310 to supply power toat least one of the first thrust generating apparatus 1360 and thegenerator 1320.

In an embodiment, when the position of the first thrust generatingapparatus 1360 is fixed and the position of the second thrust generatingapparatus 1370 is variable, the first thrust generating apparatus 1360may generate thrust in a horizontal direction, and the second thrustgenerating apparatus 1370 may generate thrust in a horizontal directionor vertical direction according to the position. Thus, when the hybridvertical take-off and landing aircraft is flying vertically, thecontroller 1330 may control the second thrust generating apparatus 1370to be driven. When the hybrid vertical take-off and landing aircraft isflying horizontally, the controller 1330 may control the first thrustgenerating apparatus 1360 and the second thrust generating apparatus1370 to be driven together.

Also, in an embodiment, the controller 1330 may control the engine 1310to supply power to the first thrust generating apparatus 1360 on thebasis of at least one of a horizontal movement distance over which thehybrid vertical take-off and landing aircraft should move for apredetermined time, a vertical movement distance, and a ratio of thehorizontal movement distance and the vertical movement distance. As anexample, during a time period in which the vertical movement distance isgreater than the horizontal movement distance and the ratio of thehorizontal movement distance and the vertical movement distance isgreater than a threshold ratio, the hybrid vertical take-off and landingaircraft may fly vertically. Since the first thrust generating apparatus1360 may generate thrust in a horizontal direction, the controller 1330may control the engine 1310 not to supply the power to the first thrustgenerating apparatus 1360 during the time period. As another example,during a time period in which the vertical movement distance is equal toor less than the horizontal movement distance and the ratio of thehorizontal movement distance and the vertical movement distance isgreater than a threshold ratio, the hybrid vertical take-off and landingaircraft may fly horizontally. Since the first thrust generatingapparatus 1360 may generate thrust in a horizontal direction and thesecond thrust generating apparatus 1370 may generate thrust in ahorizontal direction or a vertical direction according to the position,the controller 1330 may control the engine 1310 to supply power to atleast one of the first thrust generating apparatus 1360 and thegenerator 1320 during the time period.

Also, in an embodiment, the controller 1330 may change the position ofthe second thrust generating apparatus 1370 on the basis of at least oneof a horizontal movement distance over which the hybrid verticaltake-off and landing aircraft should move for a predetermined time, avertical movement distance, and a ratio of the horizontal movementdistance and the vertical movement distance. As an example, during atime period in which the vertical movement distance is greater than thehorizontal movement distance and the ratio of the horizontal movementdistance and the vertical movement distance is greater than a thresholdratio, the controller 1330 may change the direction in which therotation angle of the second thrust generating apparatus 1370 isdirected to the second direction. Thus, the second thrust generatingapparatus 1370 may generate thrust in a vertical direction. As anotherexample, during a time period in which the vertical movement distance isequal to or less than the horizontal movement distance or when the ratioof the horizontal movement distance and the vertical movement distanceis equal to or less than a threshold ratio, the controller 1330 maychange the direction in which the rotation angle of the second thrustgenerating apparatus 1370 is directed to the first direction. Thus, thesecond thrust generating apparatus 1370 may generate thrust in ahorizontal direction.

In an embodiment, the controller 1330 may receive a piloting signal ofthe hybrid vertical take-off and landing aircraft through acommunication interface. Here, the piloting signal may include apiloting instruction that controls acceleration, deceleration, altitudevariation, target altitude, target speed, or target acceleration. Thecontroller 1330 may extract a piloting instruction from the pilotingsignal and may estimate a horizontal movement distance, a verticalmovement distance, and a ratio of the horizontal movement distance andthe vertical movement distance from the piloting instruction.

Also, the controller 1330 may detect a first period, a second period,and a third period from an entire flight time of the hybrid verticaltake-off and landing aircraft. Here, the first period may refer to aperiod in which thrust is generated by the first thrust generatingapparatus 1360, the second period may refer to a period in which thrustfor vertical movement is generated by the second thrust generatingapparatus 1370, and the third period may refer to a period in whichthrust for horizontal movement is generated by the second thrustgenerating apparatus 1370.

In an embodiment, the controller 1330 may detect the first period on thebasis of whether the engine 1310 supplies power to the first thrustgenerating apparatus 1360. For example, the controller 1330 maydetermine a period in which the engine 1310 supplies power to the firstthrust generating apparatus 1360 as the first period out of the entireflight time and may exclude a period in which the engine 1310 does notsupply the power to the first thrust generating apparatus 1360 from thefirst period.

Also, the controller 1330 may detect the second period and the thirdperiod on the basis of the position of the second thrust generatingapparatus 1370. The controller 1330 may determine a period in which theaxis of rotation of the second thrust generating apparatus 1370 isdirected in the second direction as the second period and may determinea period in which the axis of rotation of the second thrust generatingapparatus 1370 is directed in the first direction as the third period.The controller 1330 may perform a control such that an overlap periodbetween the first period and the second period is shorter than anoverlap period between the first period and the third period. Thus, thethrust of the hybrid vertical take-off and landing aircraft may bedistributed and thus efficiently generated, thus enhancing flightefficiency of the hybrid vertical take-off and landing aircraft.

In an embodiment, the controller 1330 may determine the amount of powersupplied to the generator 1320 by the engine 1310 on the basis of theamount of electric power stored in the battery 1340 and may determinethe amount of power supplied to the first thrust generating apparatus1360 by the engine 1310 on the basis of the amount of power supplied tothe generator 1320 by the engine 1310. For example, for the case inwhich that the battery 1340 may store electric power of 2.5 kW, when theelectric power stored in the battery 1340 is 2.0 kW, the controller 1330may control the engine 1310 to deliver 70% of the maximum output powerto the generator 1320 and may control the engine 1310 to deliver 30% ofthe maximum output power to the first thrust generating apparatus 1360.Also, when the electric power stored in the battery 1340 is 2.0 kW, thegenerator 1320 does not need to supply the electric power to the battery1340. Thus, the controller 1330 may control the engine 1310 to deliver70% of the maximum output power to the generator 1320 and may controlthe engine 1310 to deliver 30% of the maximum output power to the firstthrust generating apparatus 1360.

Also, the controller 1330 may determine required power on the basis ofthe current position of the second thrust generating apparatus 1370.Since the controller 1330 can control the position of the second thrustgenerating apparatus 1370, the controller 1330 may confirm the mostrecent control command that controlled the position of the second thrustgenerating apparatus 1370 to confirm the current position of the secondthrust generating apparatus 1370. Also, the controller 1330 may confirminformation regarding the current position of the second thrustgenerating apparatus 1370 from the second thrust generating apparatus1370.

With the same amount of electric power supplied to the motor 1350, aflight distance of the hybrid vertical take-off and landing aircraft mayvary according to the current position of the second thrust generatingapparatus 1370. Thus, the controller 1330 may determine output power ofthe motor 1350 and may determine required power corresponding to theoutput power of the motor 1350 on the basis of the current position ofthe second thrust generating apparatus 1370.

Also, the controller 1330 may determine the amount of power supplied tothe generator 1320 by the engine 1310 on the basis of the amount ofelectric power stored in the battery 1340 and the required power. Forexample, when the required power is 4 kW and the electric power storedin the battery 1340 is 2.5 kW, the generator 1320 may produce electricpower of 1.5 kW. In this case, the controller 1330 may control theengine 1310 to deliver 60% of the maximum output power to the generator1320 and deliver 40% of the maximum output power to the first thrustgenerating apparatus 1360. Also, when the required power is 3 kW and theelectric power stored in the battery 1340 is 2.5 kW, the generator 1320may produce electric power of 0.5 kW. In this case, the controller 1330may control the engine 1310 to deliver 30% of the maximum output powerto the generator 1320 and deliver 70% of the maximum output power to thefirst thrust generating apparatus 1360.

In an embodiment, the controller 1330 may include an electric powercontroller. The electric power controller may control the generator 1320to control the amount of produced electric power and convert theelectric power produced by the generator 1320 into DC electric power. Asan example, the electric power controller may include a converter (e.g.,3-phase inverter), which may convert AC electric power produced by thegenerator 1320 into DC electric power. Also, the electric powercontroller may supply the DC electric power to the battery 1340 or maysupply the DC electric power to the motor 1350.

Also, in an example of FIG. 13, the controller 1330 may be representedas one unit. However, the controller 1330 may be composed of a firstcontroller and a second controller. Also, embodiments of the presentinvention are not limited thereto. The controller 1330 may be composedof a plurality of units. As an example, the first controller maycorrespond to the controller 250 of FIG. 2, and the second controllermay correspond to the electric power controller 240 of FIG. 2.

Also, the controller 1330 may enable a flight using only the electricpower stored in the battery 1340. For example, the controller 1330 mayenter the silence mode that supplies only the electric power stored inthe battery 1340 to the motor 1350. In this case, the controller 1330may control the engine 1310 to stop the engine 1310 and thus stopsupplying power to the generator 1320 and the first thrust generatingapparatus 1360 of the engine 1310. Thus, the controller 1330 may supplythe electric power stored in the battery 1340 to the motor 1350.

FIG. 14 is a diagram for describing first to third periods according toan embodiment.

Referring to FIG. 14, a horizontal axis of a graph of FIG. 1400 mayrepresent range, and a vertical axis may represent altitude. Thehorizontal axes of the graphs 1410 to 1430 may represent time. It isassumed that the hybrid vertical take-off and landing aircraft in FIG.14 is the same as the hybrid vertical take-off and landing aircraft 1210shown in FIG. 12. In time points 1401 to 1408, the hybrid verticaltake-off and landing aircraft may control the first thrust generatingapparatus that receives power from the engine and the second thrustgenerating apparatus that receives power by the motor to make a flight.In this case, the motor may receive at least one of the electric powerstored in the battery and the electric power produced by the generatorbut not stored in the battery. The hybrid vertical take-off and landingaircraft may take off vertically from time point 1401 to time point 1402and may make a climbing flight from time point 1402 to time point 1403.Thus, the hybrid vertical take-off and landing aircraft may flyvertically from time point 1401 to time point 1402 and may flyvertically and horizontally at the same time from time point 1402 totime point 1403. The hybrid vertical take-off and landing aircraft maymake a cruising flight from time point 1403 to time point 1404, make aloitering flight from time point 1404 to time point 1405, and make acruising flight from time point 1405 to time point 1406. Thus, thehybrid vertical take-off and landing aircraft may fly horizontally fromtime point 1403 to time point 1406. The hybrid vertical take-off andlanding aircraft may make a descent flight from time point 1406 to timepoint 1407 and may land vertically from time point 1407 to time point1408. Thus, the hybrid vertical take-off and landing aircraft may flyvertically and horizontally at the same time from time point 1406 totime point 1407 and may fly vertically from time point 1407 to timepoint 1408.

The first thrust generating apparatus may generate thrust when thehybrid vertical take-off and landing aircraft is flying horizontally.Thus, as shown in the graph 1410, the first period in which thrust isgenerated by the first thrust generating apparatus may be detected asthe period between time point 1402 and time point 1407.

Also, the second thrust generating apparatus may generate thrust forvertical movement when the hybrid vertical take-off and landing aircraftis flying vertically. Thus, as shown in the graph 1420, the secondperiod in which thrust for vertical movement is generated by the secondthrust generating apparatus may be detected as the period between timepoint 1401 and time point 1403 and the period between time point 1406and time point 1408.

Also, the second thrust generating apparatus may generate thrust forhorizontal movement when the hybrid vertical take-off and landingaircraft is flying horizontally. Thus, as shown in the graph 1430, thethird period in which thrust for horizontal movement is generated by thesecond thrust generating apparatus may be determined as the periodbetween time point 1402 and time point 1407.

Accordingly, as shown in the graphs 1410 to 1430, the hybrid verticaltake-off and landing aircraft may fly such that an overlap periodbetween the first period and the second period is shorter than anoverlap period between the first period and the third period.

FIG. 15 is an operational flowchart for describing a method ofcontrolling a mixed type hybrid vertical take-off and landing aircraftaccording to an embodiment.

Referring to FIG. 15, the hybrid vertical take-off and landing aircraftmay receive a piloting signal of the hybrid vertical take-off andlanding aircraft through a communication interface (1510).

Also, the hybrid vertical take-off and landing aircraft may control theengine to supply power to at least one of the first thrust generatingapparatus and the generator such that the overlap period between thefirst period and the second period is shorter than the overlap periodbetween the first period and the third period, on the basis of thepiloting signal (1520). Here, the first period may indicate a period inwhich thrust is generated by a first thrust generating apparatus thatreceives power from the engine, the second period may indicate a periodin which thrust for vertical movement is generated by at least onesecond thrust generating apparatus which is driven by the motor andwhose position is variable, and the third period may indicate a periodin which thrust for horizontal movement is generated by the secondthrust generating apparatus. Also, the engine may supply power to atleast one of the first thrust generating apparatus and the generator,and the generator may produce electric power using the power supplied bythe engine and supply the produced electric power to the motor or thebattery. Also, the motor may receive at least one of the electric powerstored in the battery and the electric power produced by the generatorbut not stored in the battery and may provide the power to the secondthrust generating apparatus.

The above descriptions with reference to FIGS. 1 to 14 may be applied tothe method of controlling electric power of the hybrid vertical take-offand landing aircraft shown in FIG. 15, and thus a detailed descriptionthereof will be omitted.

The method according to an embodiment may be implemented as programinstructions executable by a variety of computers and recorded on acomputer-readable medium. The computer-readable medium may also includea program instruction, a data file, a data structure, or combinationsthereof. The program instruction recorded on the recording medium may bedesigned and configured specifically for an embodiment or can bepublicly known and available to those who are skilled in the field ofcomputer software. Examples of the computer-readable medium include amagnetic medium, such as a hard disk, a floppy disk, and a magnetictape, an optical medium, such as a CD-ROM, a DVD, etc., amagneto-optical medium such as a floptical disk, and a hardware devicespecially configured to store and perform program instructions, forexample, a ROM, RAM, flash memory, etc. Examples of the programinstruction include not only machine code generated by a compiler or thelike but also high-level language codes that may be executed by acomputer using an interpreter or the like. The above exemplary hardwaredevice can be configured to operate as one or more software modules inorder to perform the operation of an embodiment, and vice versa.

Although the present disclosure has been described with reference tospecific embodiments and features, it will be appreciated that variousvariations and modifications can be made from the disclosure by thoseskilled in the art. For example, suitable results may be achieved if thedescribed techniques are performed in a different order and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents.

Accordingly, other implementations, embodiments, and equivalents arewithin the scope of the following claims.

The invention claimed is:
 1. A hybrid vertical take-off and landingaircraft comprising: an engine; a generator configured to produceelectric power using power supplied by the engine; a battery configuredto store the electric power produced by the generator; a motorconfigured to receive at least one of the electric power stored in thebattery and electric power produced by the generator but not stored inthe battery and provide the power to at least one thrust generatingapparatus; and a controller configured to select either silence mode ornormal mode, and determine the amount of electric power stored in thebattery and the amount of electric power not stored in the battery fromthe electric power supplied to the motor, based on the selected mode,wherein, in the silence mode, the controller configured to supply onlythe electric power stored in the battery to the motor, and control aduration by adjusting output power of motor, and wherein, in the normalmode, the controller configured to supply electric power not stored inthe battery to the motor.
 2. The hybrid vertical take-off and landingaircraft of claim 1, wherein the controller configured to select thesilence mode or the normal mode based on a piloting signal receivedthrough a communication interface.
 3. The hybrid vertical take-off andlanding aircraft of claim 2, wherein the controller configured tocontrol the output power of the motor according to the piloting signaland determine required power indicating electric power supplied to themotor based on the controlled output power of the motor.
 4. The hybridvertical take-off and landing aircraft of claim 3, wherein, in thesilence mode, the controller configured to control the output power ofthe motor to decrease the amount of required power to the amount ofelectric power stored in the battery or less when the amount of requiredpower is greater than the amount of electric power stored in thebattery.
 5. The hybrid vertical take-off and landing aircraft of claim3, wherein, in the silence mode, the controller configured to supplyonly the electric power stored in the battery to the motor when theamount of required power is equal to or less than the amount of electricpower stored in the battery.
 6. The hybrid vertical take-off and landingaircraft of claim 1, wherein, in the silence mode, the controllerconfigured to stop the generator from producing electric power.
 7. Thehybrid vertical take-off and landing aircraft of claim 3, wherein, inthe silence mode, the controller compares the required power and theelectric power stored in the battery to estimate the duration of thesilence mode.
 8. The hybrid vertical take-off and landing aircraft ofclaim 7, wherein the controller configured to transmit a notificationmessage through the communication interface when the estimated durationis equal to or less than a predetermined time.
 9. The hybrid verticaltake-off and landing aircraft of claim 7, wherein the controllerconfigured to decrease the amount of required power to the currentamount of required power or less when the estimated duration is equal toor less than a predetermined time.
 10. The hybrid vertical take-off andlanding aircraft of claim 1, wherein, in the silence mode, thecontroller configured to select the normal mode when the amount ofelectric power stored in the battery is decreased to a predeterminedamount of electric power.
 11. The hybrid vertical take-off and landingaircraft of claim 2, wherein: the piloting signal includes informationregarding coordinates or time at which the hybrid vertical take-off andlanding aircraft enters the silence mode; and the controller configuredto select the silence mode when the hybrid vertical take-off and landingaircraft reaches the coordinates or time.
 12. The hybrid verticaltake-off and landing aircraft of claim 2, wherein: the piloting signalincludes information regarding coordinates or time at which the hybridvertical take-off and landing aircraft exits the silence mode; and thecontroller configured to select the normal mode when the hybrid verticaltake-off and landing aircraft reaches the coordinates or time.
 13. Thehybrid vertical take-off and landing aircraft of claim 11, wherein, inthe normal mode, before reaching the coordinates or time, the controllerconfigured to adjust the amount of electric power produced by thegenerator to store the produced electric power in the battery so thatthe silence mode is entered when the coordinates or time is reached. 14.The hybrid vertical take-off and landing aircraft of claim 12, wherein:the piloting signal includes information regarding the duration of thesilence mode; and in the normal mode, the controller configured todetermine whether the silence mode is maintained during the duration andadjusts the amount of electric power produced by the generator beforereaching the coordinates or time to store the produced electric power inthe battery so that the silence mode can be maintained during theduration when it is determined that the silence mode is not maintainedduring the duration.
 15. The hybrid vertical take-off and landingaircraft of claim 1, wherein, in the normal mode, the controllerconfigured to supply only the electric power not stored in the batteryto the motor or supply the electric power not stored in the battery tothe motor together with the electric power stored in the battery. 16.The hybrid vertical take-off and landing aircraft of claim 2, whereinthe normal mode includes dash mode, wherein the controller configured torapidly accelerate the hybrid vertical take-off and landing aircraft.17. The hybrid vertical take-off and landing aircraft of claim 16,wherein: the piloting signal includes information regarding at least oneof target speed and target acceleration of the hybrid vertical take-offand landing aircraft; and the controller configured to control theoutput power of the motor so that at least one of the target speed andthe target acceleration is reached and the controller configured todetermine required power indicating electric power supplied to the motorbased on the controlled output power of the motor.
 18. The hybridvertical take-off and landing aircraft of claim 1, wherein thecontroller comprises: a first controller configured to select eithersilence mode or normal mode, wherein, in the silence mode, thecontroller configured to supply only the electric power stored in thebattery to the motor, control a duration by adjusting output power ofmotor, and wherein, in the normal mode, the controller configured tosupply electric power not stored in the battery to the motor, and asecond controller configured to determine the amount of electric powerstored in the battery and the amount of electric power not stored in thebattery from the electric power supplied to the motor, based on theselected mode.
 19. A method of controlling a hybrid vertical take-offand landing aircraft, the method comprising: selecting either silencemode or normal mode, wherein, the hybrid vertical take-off and landingaircraft comprises a battery, an engine, a generator, at least onethrust generating apparatus and a motor, wherein, the battery configuredto store electric power produced by the generator using power suppliedby the engine, wherein, the motor configured to receive at least one ofthe electric power stored in the battery and electric power produced bythe generator but not stored in the battery and provide the power to theat least one thrust generating apparatus, wherein, in the silence mode,the electric power stored in a battery is only supplied to the motor,and a duration of the silence mode is controlled by adjusting outputpower of motor, and wherein, in the normal mode, the electric power notstored in the battery is supplied to the motor; and determining theamount of electric power stored in the battery and the amount ofelectric power not stored in the battery from the electric powersupplied to the motor, based on the selected mode.
 20. A nontransitorycomputer-readable recording medium having recorded thereon a program forexecuting the method of claim 19.